Card holders of the above-mentioned type are known. They are attached e.g. to neck chains or bunches of keys so that an identification card can there be carried such that it is easily visible for possible security personnel. The reception slot of the card holder is normally provided with holding elements which project, at least in certain sections thereof, into the reception slot transversely to the direction of insertion and which establish a frictional, non-positive and/or positive engagement with a card inserted into the slot, so as to retain the card. In particular the frictional engagement can be improved when the holding elements have a comparatively high frictional coefficient.
Such a card holder is described e.g. in US patent application 2006/0117630 A1. The holding arms of this card holder enclose a card reception space which is open in a direction opposite to the direction of card insertion, said reception space being provided with a resilient insert secured in position by a positive connection. The resilient insert has two arms which extend from a yoke and from which holding segments extend whose flat heads are disposed in opposed relationship with one another, said holding segments defining between them a reception slot for the card. The holding segments are inclined in the direction of insertion so as to facilitate insertion of the card and make removal of the card more difficult.
The publication DE 75 25 780 U shows a holder with two clamping pieces defining a reception slot for flat identification carriers, a lobe formed integrally with the holder allowing said identification carriers to be retained safely.
The publication DE 650 290 A describes a price tag holder in the case of which curved portions are defined by an undulating insertion slot, said curved portions guaranteeing a tight fit of a piece of cardboard inserted into the insertion slot.
The known card holders and in particular the card holder specified in US patent application 2006/0117630 A1, which is the type of card holder referred to in the present application, are disadvantageous insofar as they cannot be used in a satisfactory manner for cards of various thicknesses or for other items to be held, such as individual thin sheets of paper or plastic material. The holding elements predetermine a fixed minimum gap width and are incapable of holding cards or the like whose thickness is smaller than this gap width. If the cards in question are, however, comparatively thick, there will be a disproportionately high increase in the force required for insertion and removal because the predetermined slot width is exceeded by far and because this entails a strong deformation of the holding elements which may, consequently, be damaged.